Humic substances failed to prevent the systemic absorption of deoxynivalenol (DON) and its adverse effects on piglets.

The aim of this study was to examine the effects of a control diet (CON, 0.25 mg DON/kg diet) or a Fusarium toxin-contaminated diet (FUS, 4.49 mg DON/kg diet) without and with humic substances (HS) (CON-HS and FUS-HS, 0.23 and 4.56 mg DON/kg diet, respectively) on piglets during a 5-week growth trial starting after weaning (6.7 ± 0.9 kg live weight, n = 20/group). Feed intake was significantly reduced by feeding the FUS containing diets by approximately 21% compared with the CON diet irrespective of HS supplementation. The decrease in live weight gain paralleled the feed intake depression and amounted to approximately 26%. Feeding the FUS diet was clearly reflected by the DON levels in blood. While only traces of DON with median concentrations of 3 ng/ml (2-5 ng/ml) and 2 ng/ml (0-3 ng/ml) were detected in piglets fed the CON and CON-HS diets, respectively, significantly higher levels of 22.5 ng/ml (7-30 ng/ml) and 23.5 ng/ml (15-32 ng/ml) were found in piglets fed the FUS and FUS-HS diet, respectively. The urinary excretion of DON and its metabolite de-epoxy-DON as percentage of DON intake was not significantly influenced by HS supplementation and amounted to 24.1 and 20.2% for groups FUS and FUS-HS, respectively. In conclusion, the tested HS preparation cannot be recommended as a DON inactivating feed supplement for pigs.